Snapback‐free reverse conducting IGBT with p‐poly trench‐collectors

A reverse conducting (RC) insulated‐gate bipolar transistor (IGBT) with p‐poly trench‐collectors is proposed. A narrow n‐drift region between two p‐poly trench‐collectors is formed as a self‐controlled electron path to the collector contact. Owing to the built‐in potential between the p‐poly and n‐drift regions, the narrow n‐drift region is depleted to offer a high‐resistance electron path at forward bias, which helps to suppress snapback. At reverse bias, holes accumulate at the n‐drift/trench‐collector interface and then the potential difference between the p‐poly and n‐drift regions mainly drops at the thin oxide layer. Thus, the narrow n‐drift becomes undepleted to offer a low‐resistance electron path, and the RC diode can be turned on. Simulation results show that the proposed RC‐IGBT is able to suppress snapback with a much smaller cell width and obtain a 21% lower turn‐off loss compared to the conventional RC‐IGBT.